CN112820633B - Gallium nitride layer and its homoepitaxial growth method - Google Patents

Abstract

The application specifically relates to a gallium nitride layer and a homoepitaxial growth method thereof, comprising the following steps: providing a gallium nitride substrate, wherein the crystal face of the gallium nitride substrate is a C crystal face, or the crystal face of the gallium nitride substrate is a crystal face which forms an off-angle alpha with the C crystal face; processing the edge of the gallium nitride substrate so that the (1-101) face is exposed by the edge of the gallium nitride substrate; and carrying out homoepitaxy on the surface of the gallium nitride substrate to obtain a gallium nitride layer which is grown in a homoepitaxy manner. The homoepitaxial growth method of the gallium nitride layer in the embodiment can avoid the formation of winged crystals, further avoid micro-cracks, fragments and pits formed by larger stress and elastic deformation between the gallium nitride layer epitaxially grown on the edge of the gallium nitride substrate and the gallium nitride layer epitaxially grown on the surface of the gallium nitride substrate, reduce dislocation density in the epitaxially grown gallium nitride layer and improve the quality of the epitaxially grown gallium nitride layer.

Description

Gallium nitride layer and its homoepitaxial growth method

Technical field

The present application belongs to the field of semiconductor technology, and specifically relates to a gallium nitride layer and its homoepitaxial growth method.

Background technique

Continuing to grow a gallium nitride layer on an existing gallium nitride (GaN) substrate is the homoepitaxial growth of gallium nitride. Then, since the crystal plane at the edge of the gallium nitride substrate is not on the same crystal plane as the surface of the gallium nitride substrate, each crystal plane can be used as a seed to epitaxially grow gallium nitride, and the epitaxial growth is on different crystal planes. The growth crystal orientation and growth rate of gallium nitride are different, so during the epitaxial growth process, it is easy to cause the growth of the edge of the gallium nitride substrate to be different from the crystal orientation of the gallium nitride host material grown on the surface of the gallium nitride substrate. Gallium nitride material; the above-mentioned gallium nitride material grown epitaxially on the edge of gallium nitride becomes wings. The existence of wings will cause the gallium nitride layer epitaxially grown on the edge of the gallium nitride substrate to be in contact with the gallium nitride liner. There is large stress and elastic deformation between the epitaxially grown gallium nitride layers on the bottom surface, which can easily lead to the formation of edge micro-cracks, fragments, and pits (pits). As shown in Figure 1, it can also cause epitaxially grown nitrogen The dislocation density in the gallium layer increases significantly, thereby reducing the yield and quality of the homoepitaxially grown gallium nitride layer.

Contents of the invention

Based on this, it is necessary to provide a gallium nitride layer and its homoepitaxial growth method that can solve the above problems in the background technology.

One aspect of this application provides a homoepitaxial growth method of a gallium nitride layer, including:

A gallium nitride substrate is provided, the crystal plane of the gallium nitride substrate is a C crystal plane, or the crystal plane of the gallium nitride substrate is a crystal plane with an offcut angle α from the C crystal plane, so The value range of the deflection angle α is: 0°≤α≤62° or 64°≤α≤90°;

Process the edge of the gallium nitride substrate so that the edge of the gallium nitride substrate exposes the (1-101) plane;

Homoepitaxial growth is performed on the surface of the gallium nitride substrate to obtain a homoepitaxially grown gallium nitride layer.

In the homoepitaxial growth method of the gallium nitride layer in the above embodiment, the edge of the gallium nitride substrate is first processed so that the edge of the gallium nitride substrate exposes the (1-101) surface, so that the When the gallium nitride layer is homoepitaxially grown on the edge and surface of the gallium nitride substrate, a gallium nitride nucleation layer with the same crystal plane is formed, and then the same or similar lateral and The gallium nitride layer is grown at a longitudinal growth rate to avoid the formation of wing crystals, thereby avoiding the large gap between the epitaxially grown gallium nitride layer at the edge of the gallium nitride substrate and the epitaxially grown gallium nitride layer on the surface of the gallium nitride substrate. The micro-cracks, fragments and pits formed by the stress and elastic deformation reduce the dislocation density in the epitaxially grown gallium nitride layer and improve the quality of the epitaxially grown gallium nitride layer.

In one embodiment, processing the edge of the gallium nitride substrate so that the edge of the gallium nitride substrate exposes the (1-101) surface includes:

Cutting the edge of the gallium nitride substrate;

The edge of the cut gallium nitride substrate is chamfered until the edge of the gallium nitride substrate exposes the (1-101) surface.

In one embodiment, processing the edge of the gallium nitride substrate so that the edge of the gallium nitride substrate exposes the (1-101) surface includes:

Cutting the edge of the gallium nitride substrate;

chamfering the edges of the cut gallium nitride substrate;

The edge of the chamfered gallium nitride substrate is selectively etched until the edge of the gallium nitride substrate exposes the (1-101) surface.

In one embodiment, processing the edge of the gallium nitride substrate so that the edge of the gallium nitride substrate exposes the (1-101) surface includes:

The edge of the gallium nitride substrate is selectively etched until the edge of the gallium nitride substrate exposes the (1-101) plane.

In one embodiment, a potassium hydroxide solution is used to selectively etch the edge of the gallium nitride substrate.

In one embodiment, the temperature of the potassium hydroxide solution is 160°C to 230°C.

In one embodiment, the concentration of the potassium hydroxide solution is between 70 g/ml and the saturated concentration of potassium hydroxide at 230°C.

In one embodiment, the etching rate of the potassium hydroxide solution for selectively etching the edge of the gallium nitride substrate is 0.005 μm/min to 2 μm/min.

In one embodiment, the gallium nitride substrate is placed in an epitaxial furnace, and homoepitaxial growth is performed using HVPE, MOCVD or ammonothermal method.

In one embodiment, after processing the edge of the gallium nitride substrate and before performing homoepitaxial growth on the surface of the gallium nitride substrate, the method further includes:

The edge-processed gallium nitride substrate is cleaned.

The present application also provides a gallium nitride layer, which is formed using the homoepitaxial growth method described in any of the above solutions.

The gallium nitride layer in this application is grown on the edge and surface of the gallium nitride substrate at the same or similar lateral and longitudinal growth rates. There is no formation of wing crystals. The nitride layer located at the edge of the gallium nitride substrate There is no large stress and elastic deformation between the gallium layer and the gallium nitride layer located on the surface of the gallium nitride substrate, which will not cause micro-cracks, fragments and pits. The dislocation density in the gallium nitride layer is low, and the nitrogen The gallium layer has higher quality.

Description of the drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. Those of ordinary skill in the art can also obtain drawings of other embodiments based on these drawings without exerting creative efforts.

Figure 1 is a schematic diagram showing the occurrence of microcracks and fragments when epitaxially growing gallium nitride on a gallium nitride substrate in the prior art.

FIG. 2 is a flow chart of a homoepitaxial growth method of a gallium nitride layer provided in an embodiment of the present application.

3 to 5 are flow charts of processing the edge of the gallium nitride substrate in the homoepitaxial growth method of the gallium nitride layer provided in different embodiments of the present application.

Detailed ways

In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the accompanying drawings. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that a thorough understanding of the disclosure of the present application will be provided.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing specific embodiments only and is not intended to limit the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Where "includes," "has," and "includes" are used herein, another component may also be added unless an explicit qualifying term is used, such as "only," "consisting of," etc. . Unless mentioned to the contrary, terms in the singular may include the plural and shall not be construed as being one in number.

In the present invention, the word "offcut" is the Chinese translation of the English word "offcut".

In one embodiment, please refer to Figure 2. This application provides a homoepitaxial growth method of a gallium nitride layer, including the following steps:

S10: Provide a gallium nitride substrate. The crystal plane of the gallium nitride substrate is the C crystal plane, or the crystal face of the gallium nitride substrate is a crystal plane with a declination angle α from the C crystal plane. The value of the declination angle α The range is: 0°≤α≤62° or 64°≤α≤90°;

S20: Process the edge of the gallium nitride substrate so that the edge of the gallium nitride substrate exposes the (1-101) surface;

S30: Perform homoepitaxial growth on the surface of the gallium nitride substrate to obtain a homoepitaxially grown gallium nitride layer.

In the homoepitaxial growth method of the gallium nitride layer in the above embodiment, the edge of the gallium nitride substrate is first processed so that the edge of the gallium nitride substrate exposes the (1-101) surface, so that the When the gallium nitride layer is homoepitaxially grown on the edge and surface of the gallium nitride substrate, a gallium nitride nucleation layer with the same crystal plane is formed, and then the same or similar lateral and The gallium nitride layer is grown at a longitudinal growth rate to avoid the formation of wing crystals, thereby avoiding the large gap between the epitaxially grown gallium nitride layer at the edge of the gallium nitride substrate and the epitaxially grown gallium nitride layer on the surface of the gallium nitride substrate. The micro-cracks, fragments and pits formed by the stress and elastic deformation reduce the dislocation density in the epitaxially grown gallium nitride layer and improve the quality of the epitaxially grown gallium nitride layer.

In step S10, please refer to step S10 in Figure 2 to provide a gallium nitride substrate. The crystal plane of the gallium nitride substrate is the C crystal plane, or the crystal plane of the gallium nitride substrate is the same as the C crystal plane. The crystal plane has a declination angle α, and the value range of the declination angle α is: 0°≤α≤62° or 64°≤α≤90°.

In one example, the crystal plane of the gallium nitride substrate may be a C crystal plane, that is, the (0001) plane. Specifically, the surface of the gallium nitride substrate on which the gallium nitride layer needs to be epitaxially grown may be a C crystal plane.

In another example, the crystal plane of the gallium nitride substrate can be a crystal plane with an offcut angle α from the C crystal plane, and the value range of the offcut angle α can be set according to actual needs. In one example , the value range of the deflection angle α can be 0°≤α≤62°, specifically it can be 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45° , 50°, 55°, 60° or 62°, etc.; in another example, the value range of the deflection angle α can be 64°≤α≤90°, specifically it can be 64°, 70°, 75°, 80°, 85°, or 90°, etc. Since the edge of the gallium nitride substrate is processed in subsequent steps, the off angle between the (1-101) plane and the C crystal plane is about 63°, and the off angle α between the crystal plane of the gallium nitride substrate and the C crystal plane is If the value is 63°, the edge of the gallium nitride substrate will be too thin due to processing problems, so the value of the off angle α between the crystal plane of the gallium nitride substrate and the C crystal plane cannot be selected to be 63°.

In step S20, please refer to step S20 in Figure 2 and Figures 3 to 5, the edge of the gallium nitride substrate is processed so that the edge of the gallium nitride substrate exposes the (1-101) surface.

In an example, referring to Figure 3, step S20 may include the following steps:

S201: Cutting the edge of the gallium nitride substrate;

S202: Selectively etch the edge of the cut gallium nitride substrate until the edge of the gallium nitride substrate exposes the (1-101) surface.

Specifically, in step S201, cutting tools such as grinding wheels or lasers may be used to cut the edge of the gallium nitride substrate, but are not limited thereto.

Specifically, in step S202, potassium hydroxide (KOH) solution can be used to selectively etch the edge of the gallium nitride substrate; in this example, after selective etching, the edge of the gallium nitride substrate is exposed ( 1-101) face.

In another example, as shown in Figure 4, step S20 may include the following steps:

S201: Cutting the edge of the gallium nitride substrate;

S202: chamfer the edge of the cut gallium nitride substrate until the edge of the gallium nitride substrate exposes the (1-101) surface.

Specifically, in step S201, cutting tools such as grinding wheels or lasers may be used to cut the edge of the gallium nitride substrate, but are not limited thereto.

Specifically, in step S202, a grinding wheel may be used, but is not limited to, to chamfer the edge of the cut gallium nitride substrate; in this example, the edge of the chamfered gallium nitride substrate is exposed (1-101) noodle.

In yet another example, referring to Figure 5, step S20 may include the following steps:

S201: Cutting the edge of the gallium nitride substrate;

S202: chamfer the edge of the cut gallium nitride substrate;

S203: Selectively etch the edge of the chamfered gallium nitride substrate until the edge of the gallium nitride substrate exposes the (1-101) surface.

Specifically, in step S201, cutting tools such as grinding wheels or lasers may be used to cut the edge of the gallium nitride substrate, but are not limited thereto.

Specifically, in step S202, a grinding wheel may be used, but is not limited to, to chamfer the edge of the cut gallium nitride substrate; in this example, the edge of the chamfered gallium nitride substrate is not exposed (1- 101) surface, but close to exposing the (1-101) surface.

Specifically, in step S203, potassium hydroxide (KOH) solution may be used to selectively etch the edge of the gallium nitride substrate.

In another embodiment, step S20 may include selectively etching the edge of the gallium nitride substrate until the edge of the gallium nitride substrate exposes the (1-101) plane. Specifically, potassium hydroxide (KOH) solution can be used to selectively etch the edge of the gallium nitride substrate.

More specifically, the potassium hydroxide solution can be a high-temperature and high-concentration potassium hydroxide solution. The temperature of the potassium hydroxide solution is 160°C to 230°C. For example, the temperature of the potassium hydroxide solution can be 160°C, 180°C, 200℃ or 230℃ etc. The concentration of the potassium hydroxide solution is between 70g/ml (grams per milliliter) and the saturation concentration of potassium hydroxide at 230°C. In this example, the concentration of the potassium hydroxide solution not only includes 70g/ml and hydrogen at 230°C. Several numerical ranges between the saturation concentration of potassium oxide, including 70 g/ml, and the saturation concentration of potassium hydroxide at 30°C. Preferably, the concentration of the potassium hydroxide solution can be 100g/ml~360g/ml, for example, it can be 100g/ml, 150g/ml, 200g/ml, 250g/ml, 300g/ml or 360g/ml, etc.; more Preferably, the concentration of the potassium hydroxide solution can be 110g/ml~300g/ml, for example, it can be 110g/ml, 150g/ml, 200g/ml, 250g/ml or 300g/ml, etc.

In one example, the etching rate of the potassium hydroxide solution for selectively etching the edge of the gallium nitride substrate can be set according to actual needs. In this example, the potassium hydroxide solution selectively etches the edge of the gallium nitride substrate. The etching rate for selective etching can be 0.005μm/min~2μm/min; specifically, the etching rate can be 0.005μm/min, 0.01μm/min, 0.05μm/min, 0.1μm/min, 0.5μm /min, 1μm/min, 1.5μm/min or 2μm/min, etc.

In an optional example, step S20 may also include a step of cleaning the gallium nitride substrate after edge processing. Specifically, the existing cleaning process commonly used in the semiconductor field can be used to clean the gallium nitride substrate after edge processing. For example, but not limited to, deionized water can be used to clean the gallium nitride substrate after edge processing.

It should be noted that after cleaning the edge-processed gallium nitride substrate, the gallium nitride substrate needs to be dried. Specifically, the gallium nitride substrate can be dried using, but is not limited to, a heating process. .

In step S30, please refer to step S30 in FIG. 2 to perform homoepitaxial growth on the surface of the gallium nitride substrate to obtain a homoepitaxially grown gallium nitride layer.

In one example, the gallium nitride substrate can be placed in an epitaxial furnace, using HVPE (Hydride VaporPhase Epitaxy, hydride vapor phase epitaxy), MOCVD (Metal-organic Chemical VaporDePosition, metal organic compound chemical vapor deposition) or ammonia thermal Method for homogeneous extension. The temperature and time of epitaxial growth are known to those skilled in the art and will not be described again here.

In the process of epitaxial growth of the gallium nitride layer, a nucleation layer is first formed, and then each nucleation layer grows horizontally and vertically at the same time, merging and gathering in the transverse direction to form a continuous block, and then in the longitudinal direction. Growth in thickness. The formed nucleation layer generally exists in the form of a hexahedron, and the formation plane is the (1-101) plane. In the homoepitaxial growth method of the gallium nitride layer in the above embodiment, the edge of the gallium nitride substrate is first processed so that the edge of the gallium nitride substrate exposes the (1-101) surface, so that the When the gallium nitride layer is homoepitaxially grown on the edge and surface of the gallium nitride substrate, a gallium nitride nucleation layer with the same crystal plane is formed, and then the same or similar lateral and The gallium nitride layer is grown at a longitudinal growth rate to avoid the formation of wing crystals, thereby avoiding the large gap between the epitaxially grown gallium nitride layer at the edge of the gallium nitride substrate and the epitaxially grown gallium nitride layer on the surface of the gallium nitride substrate. The micro-cracks, fragments and pits formed by the stress and elastic deformation (as shown in Figure 1) reduce the dislocation density in the epitaxially grown gallium nitride layer and improve the quality of the epitaxially grown gallium nitride layer.

In yet another embodiment, the present application also provides a gallium nitride layer. The gallium nitride layer is formed by using the above-mentioned homoepitaxial growth method of the gallium nitride layer.

The gallium nitride layer in this application is grown on the edge and surface of the gallium nitride substrate at the same or similar lateral and longitudinal growth rates. There is no formation of wing crystals. The nitride layer located at the edge of the gallium nitride substrate There is no large stress and elastic deformation between the gallium layer and the gallium nitride layer located on the surface of the gallium nitride substrate, which will not cause micro-cracks, fragments and pits. The dislocation density in the gallium nitride layer is low, and the nitrogen The gallium layer has higher quality.

The technical features of the above-described embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-described embodiments only express several implementation modes of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all fall within the protection scope of the present application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims (11)

1. A homoepitaxial growth method of a gallium nitride layer, characterized by comprising: A gallium nitride substrate is provided, the crystal plane of the gallium nitride substrate is a crystal plane with an off angle α from the C crystal plane, and the value range of the off angle α is: 0°≤α≤62°; Process the edge of the gallium nitride substrate so that the edge of the gallium nitride substrate exposes the (1-101) surface; Homoepitaxial growth is performed on the surface of the gallium nitride substrate to obtain a homoepitaxially grown gallium nitride layer. 2. The homoepitaxial growth method of a gallium nitride layer according to claim 1, characterized in that the edge of the gallium nitride substrate is processed so that the edge of the gallium nitride substrate is exposed. (1-101) covers: Cutting the edge of the gallium nitride substrate; The edge of the cut gallium nitride substrate is chamfered until the edge of the gallium nitride substrate exposes the (1-101) surface. 3. The homoepitaxial growth method of a gallium nitride layer according to claim 1, characterized in that the edge of the gallium nitride substrate is processed so that the edge of the gallium nitride substrate is exposed. (1-101) covers: Cutting the edge of the gallium nitride substrate; chamfering the edges of the cut gallium nitride substrate; The edge of the chamfered gallium nitride substrate is selectively etched until the edge of the gallium nitride substrate exposes the (1-101) surface. 4. The homoepitaxial growth method of a gallium nitride layer according to claim 1, characterized in that the edge of the gallium nitride substrate is processed so that the edge of the gallium nitride substrate is exposed. (1-101) covers: The edge of the gallium nitride substrate is selectively etched until the edge of the gallium nitride substrate exposes the (1-101) surface. 5. The homoepitaxial growth method of a gallium nitride layer according to claim 3 or 4, characterized in that a potassium hydroxide solution is used to selectively etch the edge of the gallium nitride substrate. 6. The homoepitaxial growth method of a gallium nitride layer according to claim 5, wherein the temperature of the potassium hydroxide solution is 160°C to 230°C. 7. The homoepitaxial growth method of a gallium nitride layer according to claim 5, wherein the concentration of the potassium hydroxide solution is between 70 g/ml and the saturated concentration of potassium hydroxide at 230°C. 8. The homoepitaxial growth method of a gallium nitride layer according to claim 5, characterized in that the potassium hydroxide solution selectively etches the edge of the gallium nitride substrate at an etching rate of 0.005μm/min~2μm/min. 9. The homoepitaxial growth method of the gallium nitride layer according to claim 1, characterized in that the gallium nitride substrate is placed in an epitaxial furnace, and HVPE, MOCVD or ammonothermal method is used for homoepitaxial growth. . 10. The homoepitaxial growth method of a gallium nitride layer according to claim 1, characterized in that after processing the edge of the gallium nitride substrate, the surface of the gallium nitride substrate is Before homogeneous extension, it also includes: The edge-processed gallium nitride substrate is cleaned. 11. A gallium nitride layer, characterized in that the gallium nitride layer is formed by the homoepitaxial growth method according to any one of claims 1 to 10.